Volume 15 Issue 9, September 2019

Efforts to demonstrate the feasibility of fusion power can benefit from studies of fundamental questions in plasma physics carried out in simplified devices.

Photonic circuits naturally implement boson sampling, a quantum algorithm that is classically hard to solve. Four photon pairs produced and processed within a single silicon chip have now been used to run it, a step towards besting classical computers.

The superconductor–insulator phase transition is a quantum phenomenon that reveals a competition between the superconducting phase order and charge localization. Now, microwave spectroscopy is shown to be a promising approach to investigate this effect in controllable one-dimensional Josephson arrays.

Two-level quantum systems are routinely excited by resonant pump beams. Experiments now show resonant excitation through dichromatic, detuned pumps — providing a coherent control technique that will also aid single-photon emission from solid-state devices.

A rich pattern of fractional quantum Hall states in graphene double layers can be naturally explained in terms of two-component composite fermions carrying both intra- and interlayer vortices.

A type of stochastic neural network called a restricted Boltzmann machine has been widely used in artificial intelligence applications for decades. They are now finding new life in the simulation of complex wavefunctions in quantum many-body physics.

Transport data reveal interlayer composite fermion fractional quantum Hall states in double-layer graphene. The authors also show that these can pair up to form an interlayer composite fermion exciton condensate.

It is shown that composite fermions in the fractional quantum Hall regime form paired states in double-layer graphene. Pairing between layers gives a phase similar to an exciton condensate and pairing within a layer may lead to non-abelian states.

Disorder present in monolayer NbSe₂ is found to be able to enhance its superconductivity. A systematic study reveals the origin—disorder-induced multifractality of the electron wavefunctions strengthens the local interactions.

Three-dimensional spin–orbit coupling is synthesized for ultracold fermions trapped in optical Raman lattice. The band structure bearing a nodal-line semimetal character is reconstructed through a series measurement of spin textures.

Machine learning can help to identify quantum phase transitions. Here a trained neural network is applied to single-shot density images from a quantum gas experiment, realizing the Haldane model and the Bose–Hubbard model.

Quantum gas microscopes provide high-resolution real-space snapshots of quantum many-body systems. Now machine-learning techniques are used in choosing theoretical descriptions according to the consistency of their predictions with these snapshots.

Experiments report the generation and manipulation of eight photons on a silicon chip. Integrating linear and nonlinear photonic circuitry, three different boson sampling approaches are implemented and used to compute molecular vibronic spectra.

A Josephson junction array is used to show the phase mode associated with superconductivity surviving deep in the insulating regime at high frequency. This generates a device with an effective fine structure constant larger than unity.

A general scheme for a resource-efficient probabilistic detection of multipartite entanglement is demonstrated on six-partite cluster states.

A quantum two-level system can be coherently excited by a phase-locked dichromatic electromagnetic field. This technique can make single-photon generation more efficient as the pump light does not overlap in frequency with the emitted single photons.

This investigation of the two-dimensional superconductor–insulator transition in NbSe₂ shows a strong dependence on the number of layers, and that fully dissipationless superconductivity is almost absent in the monolayer.

Despite being a charge insulator, YbB₁₂ behaves like a thermal metal. Low-temperature heat-transport measurements of this compound showed its gapless, itinerant and charge-neutral excitations.

A general theoretical picture regarding the generation and the detection of extremely short pulses of squeezed vacuum light is provided, allowing the treatment of arbitrary wavepackets of quantum light intrinsically in the time domain.

A theory that reinterprets the electrical conductivity of insulating fluids in terms of integer ionic charges that correspond to oxidation states is put forward and tested numerically.

The rate at which proteins are imported into the nucleus of a cell is shown to be regulated by their mechanical unfolding, a mechanism that identifies the nuclear pore machinery as a highly sensitive force detector.

From determining the compound interest on borrowed money to gauging chances at the roulette wheel in Monte Carlo, Stefanie Reichert explains that there’s no way around Euler’s number.